Susceptibility of Near-Neutral PH SCC to Plastically Pre-strained API X60 And X70 Pipeline Steels

Strain-based design for pipelines requires immense understanding of the postyield mechanical behaviour of materials with different microstructure. On the other, it subject to early cracking due to the presence of corrosive environment and stresses. In this paper effect of plastic pre-strain on Mechanochemistry and its sensitivity to Stress corrosion cracking of X60 pipe steel was investigate in NS4 Solution using tafel curve measurements (in different scanrate), Slow strain rate test (SSRT) and electrochemical noise analysis (at OCP); then compared with X70 pipe steel series by applying 5% strains equally. Damage Analysis shows that SCC resistance to plastic pre-strain decrease drastically in both material. Although, Susceptibility of Plastically Pre-strained API X60 to SCC in NS4 Solution is more than X70 series As anodic dissolution may occur when the steel is polarized catholically at higher scan rate. The correlation of the ratio of the reduction in area in NS4 solution to that in air (RASCC/RAair) with the API grade is microstructure dependent

Keywords:

SCC (Stress Corrosion Cracking) , pre-strain , API , SSRT(Slow strain rate test) , electrochemical noise analysis